Syrian government forces on Wednesday advanced towards the ancient city of Palmyra, which is under the control of the Islamic State terrorist militia, a monitoring group said.
The Syrian Observatory for Human Rights said the Syrian army was just 2 kilometres away from Palmyra.
The central Syrian city, built on an oasis, is a UNESCO World Heritage Site with monuments thousands of years old.
"The regime troops have reached the south-western outskirts of Palmyra," the Observatory's head Rami Abdel-Rahman told dpa.
Syrian state news agency SANA meanwhile quoted an unnamed military official as saying government forces had taken control of al-Hayal Mountain, which overlooks Palmyra on its south-western edge.
The troops were in the process of dismantling mines planted by jihadists along the access route to the city, SANA said.
The Syrian army, backed by Russian warplanes, started a major offensive to retake control of Palmyra two weeks ago.
The city, in the province of Homs, has been under Islamic State's control since May 2015. The radical group's takeover raised international fears about the fate of the city's artefacts.
In August, Islamic State destroyed several famous sites in the city, including the more than 2,000-year-old Baalshamin Temple.
Meanwhile, German Foreign Minister Frank-Walter Steinmeier said he sees no role for Syria's longtime president in the future leadership of that country.
Steinmeier said he could not imagine Syrian President Bashar al-Assad being acceptable to all population groups in that country after 250,000 deaths and millions of refugees caused by a civil war, continuing for more than five years.
Steinmeier, in Moscow for a series of meetings with Russia's leadership, expressed hope that the Syrian government will engage in serious consultations in Geneva to negotiate a peaceful political transition process.
Russia is a close ally of Syria's current government and has been a strong backer of the peace process.
UN-brokered peace talks between Syria's ruling regime and political opposition are under way in Geneva and being mediated by UN Syria envoy Staffan de Mistura.
Steinmeier told reporters in televised comments that Syria's government and rebel groups should exchange prisoners in an effort to achieve a unified state.
Steinmeier and Russian Foreign Minister Sergei Lavrov said they had discussed the problem of international terrorism in depth, following the recent attacks in Brussels, and their countries would seek to collaborate more closely against terrorism.
"It is in our joint interest to act against this threat," Steinmeier said.
Lavrov called for European unity. "I hope that the Europeans will set aside geopolitical game playing in the face of terrorism and unite," he said.
Steinmeier expressed similar sentiment at a later meeting with Russian President Vladimir Putin.
"As for the fight against terrorism, we clearly need to concentrate our efforts to prevent this threat," the German minister said.
"As for Syria, we have definitely made some progress over these last two to three months ... I am pleased that there are trends in our bilateral relations that give cause for optimism," Steinmeier said.
He was also scheduled to meet US Secretary of State John Kerry in Moscow for dinner later Wednesday, the German embassy confirmed to dpa.